Lighting systems incorporating ceiling-mounted lighting fixtures or luminaires are routinely used to illuminate commercial floor space and objects residing on the floor space within the illuminated area. Luminaires generally consist of an assembly of components, such as lamps, ballasts, and reflectors, which cooperate to produce and direct light. Luminaires that incorporate fluorescent lamps are the most commonly used commercial light sources due to their relatively high efficiency, diffuse light distribution characteristics, and long operating life.
Fluorescent lamps are long tubes that contain mercury and argon gas. Electrodes sealed into each end of a tube allow the lamp to conduct an electric current, thereby emitting ultra-violet radiation. The tube of a fluorescent lamp is a glass envelope. The inside surface of the tube is coated with a phosphor that provides visible illumination when excited by ultra-violet radiation. The phosphor, or fluorescent coating, may be harmful to a person's eyes. The glass envelope is infamous for its ability to shatter and blanket an area with sharp glass. The neurological toxicities associated with mercury exposure are well documented. Additionally, only a portion of the radiation produced by a fluorescent lamp is ever converted into visible light. As with incandescent light bulbs, the excess radiation produces heat. Collectively, the heat generated by these lamps places a tremendous burden on the air conditioning system of a building, especially during the summer months in warmer climates.
Many conventional fluorescent lighting fixtures are adapted for recessed mounting in a suspended ceiling, in which the lighting fixtures have bulky box enclosures or troffers supported by adjacent pairs of T-bars comprising the support structure of the ceiling. In addition to housing and supporting the other components of the lighting fixture, the troffer provides a fire protection enclosure.
Over the lifetime of a commercial lighting system, the expenditures associated with operating and maintaining that system are significant. As lighting fixtures age and deteriorate, the light-emitting ability degrades and the light output per unit of consumed electrical energy is significantly reduced. Modern ballasts, lamps and reflectors are available that would significantly enhance the light-emitting ability of the lighting system and also significantly enhance the energy efficiency by reducing the power consumption. As a result, the light output could be increased while simultaneously reducing the associated energy costs. Thus, it is desirable to replace obsolete lighting fixtures with lighting fixtures that incorporate modern ballasts, lamps and lamp sockets to hold the lamps, and reflectors. Existing lighting fixtures of commercial light systems cannot be easily upgraded to replace obsolete lighting fixtures with lighting fixtures that incorporate modern components, or refurbished with modern components to reverse the effects of deterioration. Conventional fluorescent lighting fixtures and available retrofitting kits are unsatisfactory for upgrading existing lighting systems because, among other things, the existing lighting fixtures must first be removed or, at the least, significantly modified by removing certain components from the existing lighting fixtures before the upgrade can be performed. Retrofitting with conventional fluorescent luminaires or available retrofitting kits is a labor-intensive and lengthy process that significantly disrupts commercial operations during the retrofit process. Furthermore, the removed lighting fixtures or components generate a waste stream for disposal or recycling. Disposal poses significant environmental concerns from hazardous or toxic substances in the removed components, such as mercury in the fluorescent lamps and chemicals including polychlorinated biphenyls (commonly referred to as PCB's) in the ballasts.